Using OD in 1/4 mi.?

[MAX PSI]

Has anyone ever use OD in racing? I mean gear the rear to something around 5.13:1 so you can use 4th. If so would it be quicker or slow it down? I'm not worried about fuel milage but I have broken an overdrive carrier in the past. I thought someone was working on a bilet carrier. Is it available? If one would set a 200r4 up this way would it lighten the load on the trans? Could you use a tighter convertor to take advantage of the lower overall 1st gear? I know the 1-2 shift would come on in a hurry but I can have that shift done automatically. I might setup my trans this way to see how it works unless someone talks me out of it.

 

[monte_383]

I have mine setup to use OD in the 1/4. Since I don't have a charged engine like most guys on here, I can get away with lower gears in the rear (i.e. 4.56's), it actually helps me. If you put too low of a gear behind a turbo engine (or so I have heard), the engine isn't under enough of a load to make as much boost, which is bad. I know personally in my WRX, full boost in first gear doesn't come on until about 3400( I have a bigger non-stock T3/T4 Garret doing the duty in place of the puny Mitsubishi turbo), but if I'm cruising uphill at about 2500 in 5th gear and punch it I get full boost immediately, on account of the load. Maybe some of the faster guys will chime in, but I think the 3.42's the TB's come with is about optimal. HTH's- Chuck

 

[GNVAIR]

I seem to remember Geno saying he uses 4th gear in his GN and has run 9.90's. But I also seem to remember he is still using 3.42 gears. I dont really think there is anything to be gained in the low 11 second range. Maybe down in the low 10 second range it might make a difference, but if you talk to most of the guys on this board you will find most are using 3 gears. The real fast guys are using th400's and thats only a 3 speed. So think it over before trying it.

 

[MAX PSI]

I'm building my combo to compete in TSM. It will be a low 10 sec car. I'll be leaving off a trans brake so that takes care of the load needed to build boost. I still may try it . I use a 9" f--- so gear swaps are some what easier. Keep the comments coming.

 

[Blown&Injected]

At about 116 my car seems like it is screaming and wanting to go to 4th gear - but I now have a bigger cam and I am running taller tires.

I have not yet tried locking the converter - that may help keep it in 3rd.

 

[GNVAIR]

Remember that locking the convertor is almost like having another gear change.
There are a lot of 7 and 8 second cars out there running Powerglides with a lock up convertor. Speaking with one guy that has been running one in a Mustang, I was told it was like having a 3 speed.

 

[WE4]

Billet od planets

will be out next month. March 1, 2003.

PTS XTREME has them.

 

[TWIN86GNS]

About 10 years ago we were thinking the same way, run a 5.13 gear and use 4th. We ended up running a 4.86 and we didn't like it. The car didn't go any faster and we had trouble with our 200-4R not shifting 1-2 properly. I think we also had trouble with the governor, it didn't seem to like to spin that quickly.

When we first tried this, the technology for chips, injectors and turbo's wasn't nearly what it is today. You very well may be able to make this combination work, but the stock 3.42 gears are known to work.

We had previously used 3.90 and went back to stock, then the 4.86 and went back to stock. The stock 3.42 gear and a 28 or 28.5" tall tire seems to work real well with our low reving torque monster engines.

Good luck with what ever you decide,


Paul Beal
pbeal@sympatico.ca

 

[gnx7]

My conversion limits me to 4:10's and 26" tall tire so I leave it in OD out of the box. It shifts into OD just after the 1/8th mile marker. My best 1/8th is 94mph and 115mph at the big end with unlocked TC. I hope to lock the convertor and let it shift into OD and get a better et and more MPH.

I agree 3:42's with a 28" tall tire is about perfect in 3rd gear and under 130mph.... past that you probably want to use OD.

As my car is light.... and generates less load than a heavy car... I plan to run some 3:08's or 3:27's gears in a F*rd 8.8" ladder bar'd setup out back one day. This should be good for some nice 140mph+ 3rd gear blasts in late 2003.... early 2004.

-GNX7

 

[MAX PSI]

Thanks bruce, I've already broke one carrier. I will be giving you a call in the near future. Do you have any suggestion on running my transmission this way? Will I gain anything or is it worthwhile
to do it?

Turbo86GNS>>>This is the comment I am looking for. Turbo technology is different then 10 years ago. I will probably set it up with the current 3:73 gears 28" tall tires then swap in the lower gears and see if it makes a difference. Of course the tune up will be different for each set up. We will have to wait and see.

 

[TWIN86GNS]

Originally posted by MAX PSI
Turbo86GNS>>>This is the comment I am looking for. Turbo technology is different then 10 years ago. I will probably set it up with the current 3:73 gears 28" tall tires then swap in the lower gears and see if it makes a difference. Of course the tune up will be different for each set up. We will have to wait and see.

Phil,

Not only is the technology for turbo's, chip's and injector's far ahead of where it was 10 years ago but there has been huge leaps in hard parts available for our transmissions. One of the reasons we didn't run the 4.86 (actually I think they were 4.88's) gears for very long is we were having trouble keeping the transmissions running with that gear ratio. You will probably be able to do it with what is available today.

Good luck and let us know how you make out.

Paul Beal
pbeal@sympatico.ca